The big reason heel striking when running is bad for your legs is it naturally produces 2 major forms of impact: vertical loading and the vertical ground reaction force, causing them to exceed tolerance, which is the primary cause of most major injuries, like long bone injuries (femur and shin fracture). The only way to prevent these forces from rising to pain and injury predisposing levels is not with more underfoot cushioning, but by changing your heel strike to a forefoot strike. Read more here!
